JP4489935B2

JP4489935B2 - Wireless communication system

Info

Publication number: JP4489935B2
Application number: JP2000373985A
Authority: JP
Inventors: 充村本; 金見佐々木
Original assignee: Hitachi Kokusai Electric Inc
Current assignee: Hitachi Kokusai Electric Inc
Priority date: 2000-12-08
Filing date: 2000-12-08
Publication date: 2010-06-23
Anticipated expiration: 2020-12-08
Also published as: JP2002176670A; US6961580B2; US20020072373A1

Description

【０００１】
【発明の属する技術分野】
本発明は、無線通信エリアを複数の基地局を配置することにより複数のセルに分割し、複数のセルで同一の周波数を繰り返して用いることを可能ならしめる無線通信システムに関し、これにより、例えば、準ミリ波帯やミリ波帯の限られた周波数帯域を有効利用した加入者系無線アクセスシステムのＰ−ＭＰシステムを実現する技術に関する。
【０００２】
【従来の技術】
例えば、ＷＬＬ（wireless local loop）あるいはＦＷＡ（Fixed wireless access）などと称せられる無線通信を用いた加入者系無線アクセスシステムが知られている。加入者系無線アクセスシステムは、図８に示すように、電気通信事業者が設置する基地局１と複数の利用者宅地側にそれぞれ設置される加入者局２とを無線通信で接続するものであり、基地局１と加入者局２とが無線通信することで、異なる加入者局２に接続されたＬＡＮ３の間でデータ通信することができ、また、基地局１に接続された公衆通信網などのバックボーンネットワーク４を介して更に他の加入者ＬＡＮとデータ通信することができる。
基地局１は多数の加入者局２を収容しており、このような一対多方向方式の無線設備はＰ−ＭＰ（Point−Multi Point）システムと呼ばれている。
【０００３】
このような基地局１を複数分散配置することにより、一定の地域を全面的にカバーして多数の加入者局２にサービスを提供することができるが、限られた周波数資源を有効に利用するため、同一の通信周波数を繰り返して使用しなければならない。
このような周波数の繰り返し使用は、自動車や携帯電話等に見られる移動通信の分野では昔から行われていたが、干渉を防止するため同一周波数を隣接の基地局で用いることはできなかった。
【０００４】
前記Ｐ−ＭＰシステムは準ミリ波帯やミリ波帯といった高い通信周波数を使用し、高利得なアンテナを用いて見通し内の無線通信を行うもので、この標準規格はＡＲＩＢＳＴＤ−Ｔ５９で定められている。この標準規格によれば、通信周波数は２６ＧＨｚ帯あるいは３８ＧＨｚ帯を用い、加入者局には２０ｄＢｉ以上の高利得アンテナを用いなければならないことが定められている。
【０００５】
このような事情から、基地局１のアンテナ６にパラボラアンテナやセクタアンテナなどの指向性アンテナを用いて周波数の繰り返し使用及び高利得を実現していた。
複数のパラボラアンテナを基地局に設けて、これらパラボラアンテナを互いに異なる方向へ向けて水平面の全方位を複数のセクタに分割し、セクタ分割により周波数の繰り返し使用を実現するとともに高利得を実現していた。また、セクタアンテナは、例えば図９に示すように、円盤状のアンテナ基板１０を遮蔽板１１により４つのセクタＡ〜Ｄに分割し、各セクタＡ〜Ｄにアンテナ素子１２を設けて各セクタＡ〜Ｄをそれぞれ指向性アンテナに構成した構造であり、セクタＡ〜Ｄにより水平面の全方位を４分割し、セクタ分割により周波数の繰り返し使用を実現するとともに高利得を実現していた。
【０００６】
そして、加入者系無線アクセスシステムでは、このような基地局１の各セクタに収容される固定加入者局２においても指向性アンテナ７を用いて、通信周波数の繰り返し使用によるセクタ間での干渉を防止している。
ここで、基地局を略中心として当該基地局による通信サービス領域をセルとして形成し、複数の基地局を分散配置することにより広い領域を複数のセルによりカバーする無線通信システムにおけるセルの構成法として、特開平１０―４２３５２号公報に記載された発明が知られている。
【０００７】
この発明は図１０に示すようなものであり、同図において、Ｂ１〜Ｂ４は基地局で、各基地局の通信サービスエリア（セル）を便宜上六角形で示し、Ｆ１〜Ｆ３は各アンテナ（セクタ）の使用周波数（チャネル）を示している。すなわち、この発明では、セル内のセクタｍ個（ｍは２以上の正数）毎に同一の周波数となるように設定して、セクタ間での干渉を防止しようとするものである
【０００８】
ここで、この発明のような構成とすると、Ｃ１は基地局Ｂ２のＦ２チャネルを使用するセクタに属する加入者局のひとつであるが、経路を図１０中に矢印で示すように、この加入者局Ｃ１が同一チャネルによる干渉を受けるあるいは与える可能性のある最も近接した基地局はＢ４である。このような構成とすると、同一チャネル干渉は1セルの間隔を離して起こり得るが、この程度の干渉であれば所期の通信品質を維持することができ実用上の支障は生じない。
【０００９】
しかしながら、実際の基地局の配置は机上検討の通りには行かないことも多く、周囲の環境や設置場所の確保など諸般の事情に左右されることがあり、セル間での干渉が生じてしまう。図１１は基地局Ｂ３の設置位置が正規の場所からずれて配置された場合の例を示しており、基地局Ｂ３のＦ２チャネルを使用するセクタに属する加入者局Ｃ２は隣接する基地局Ｂ２のＦ２チャネルを使用するセクタとの間で干渉を生じる可能性がある。
また、このような六角形で構成されるセル配置は最低でも３つないとセルの面展開を行うことができなかった。また、使用できるチャネルが４つあったとしても、この４つのチャネルを効率的に使用することは難しいことが予想される。
【００１０】
【発明が解決しようとする課題】
本発明は、隣接セルとの間の干渉を防止し、また、使用する通信周波数が最低２つ以上あれば実現可能なセル配置構造を有する無線通信システムを提供することを目的としている。
特に、本発明は、従来のセルラーシステムでは採用されていいない4セクター構成により加入者系無線アクセスシステムに最適なセル配置を提供することを目的としている。
なお、本発明の更なる目的は以下の説明において明らかなところである。
【００１１】
【課題を解決するための手段】
本発明に係る無線通信システムは、基地局を略中心として当該基地局による通信サービス領域をセルとして形成し、複数の基地局を分散配置することにより複数のセルを形成した通信システムであり、基地局に指向性アンテナを用いることにより当該基地局のセルを４つのセクタに分割し、隣接するセル間では隣接するセクタに同一の通信周波数を設定している。
【００１２】
すなわち、隣接する４つのセルを捉えてみると、これらセルの隣接するセクタでは各セルの基地局は水平面内で放射内方へ指向性を有している。そして、これら隣接セクタ内に固定加入者局をセクタ内の基地局への指向性をもって設置すると、当該固定加入者局は自己が属する基地局方向への指向性を呈するが他の隣接セクタの基地局に対して背を向ける（すなわち、隣接セクタの基地局と固定加入者局とはその指向性が対向することがない）こととなり、当該固定加入者局の無線通信に隣接セクタの基地局との関係の干渉が生じることがない。
【００１３】
また、本発明に係る無線通信システムは、基地局を略中心として当該基地局による通信サービス領域をセルとして形成し、複数の基地局を分散配置することにより複数のセルを形成した通信システムであり、基地局に指向性アンテナを用いることにより当該基地局のセルを４つのセクタに分割し、同一のセル内では隣接するセクタに異なる通信周波数を設定し、直交方向で隣接する他のセルとは各セクタの通信周波数設定が鏡面関係で、当該直交方向の間で隣接する他のセルとは各セクタの通信周波数設定が左右反転の鏡面関係として、隣接するセル間では隣接するセクタに同一の通信周波数を設定している。
また、本発明に係る無線通信システムは、上記基地局のセルを地磁気方向を基準とした４つの方向へ指向するセクタに分割している。
【００１４】
例えば、後述する図１に示すように、基地局Ｂ５のセルをそれぞれ北西、北東、南東、南西を指向する４つのセクタに分割し、それぞれのセルに通信周波数Ｆ１、Ｆ３、Ｆ２、Ｆ４を設定した場合、当該基地局Ｂ５に隣接する８つのセルを捉えてみると、南北及び東西方向で隣接する４つのセルＢ２、Ｂ８、Ｂ４、Ｂ６では、セルＢ５に対して鏡面関係のセクタ周波数設定とし、当該直交方向の間の方向で隣接する４つのセルＢ１、Ｂ３、Ｂ９、Ｂ７では、セルＢ５に対して左右反転の鏡面関係のセクタ周波数設定とすると、セルに隣接する８つのセルとの間で隣接するセクタに同一の通信周波数を設定することができる。
なお、この配置の基準となる直交方向は地磁気の方向を基準として設定するのが好ましく、このようにすれば設置作業において、遠隔の隣接する基地局の位置を予め把握せずとも、作業者は磁石をもって隣接する基地局の位置関係を把握することができ、広大なエリア内でも上記のような周波数設定を行うセル配置及びセクタ分割を行うことができる。
【００１５】
また、本発明に係る無線通信システムは、基地局を略中心として当該基地局による通信サービス領域をセルとして形成し、複数の基地局を分散配置することにより複数のセルを形成した通信システムであり、基地局に指向性アンテナを用いることにより当該基地局のセルを４つのセクタに分割し、隣接するセル間では隣接するセクタに同一の通信周波数及び偏波方式を設定している。
すなわち、同一の通信周波数でも偏波方式を違えることにより干渉を防止することができるが、本発明では、上記のように隣接するセルの隣接するセクタ間ではセクタ内の固定加入者局は他のセクタの基地局と指向性が対向することがないので（加入者局が２０ｄＢｉ以上の高利得アンテナを用いる場合は特に）、隣接するセル間の隣接するセクタに同一の通信周波数及び偏波方式を設定している。
【００１６】
また、本発明に係る無線通信システムは、基地局を略中心として当該基地局による通信サービス領域をセルとして形成し、複数の基地局を分散配置することにより複数のセルを形成した通信システムであり、基地局に指向性アンテナを用いることにより当該基地局のセルを４つのセクタに分割し、同一のセル内では隣接するセクタに通信周波数と偏波方式との少なくともいずれか一方を異ならせて設定し、直交方向で隣接する他のセルとは各セクタの通信周波数及び偏波方式の設定が鏡面関係で、当該直交方向の間で隣接する他のセルとは各セクタの通信周波数及び偏波方式の設定が左右反転の鏡面関係として、隣接するセル間では隣接するセクタに同一の通信周波数及び偏波方式を設定している。すなわち、同一セルの隣接セクタ間では同一の通信周波数でも垂直偏波と水平偏波、右旋円偏波と左旋円偏波などといったように偏波方式を違えることにより干渉を防止することができ、隣接セルの隣接セクタ間では上記のように指向性が対向することがないので同一の通信周波数及び偏波方式を設定することができる。
また、本発明に係る無線通信システムは、上記基地局のセルを地磁気方向を基準とした４つの方向へ指向するセクタに分割している。
【００１７】
例えば、後述する図５に示すように、基地局Ｂ５のセルをそれぞれ北西、北東、南東、南西を指向する４つのセクタに分割し、それぞれのセルに通信周波数及び偏波方式（Ｖ：垂直偏波、Ｈ：水平偏波）をＦ１Ｖ、Ｆ２Ｖ、Ｆ１Ｈ、Ｆ２Ｈを設定した場合、当該基地局Ｂ５に隣接する８つのセルを捉えてみると、南北及び東西方向で隣接する４つのセルＢ２、Ｂ８、Ｂ４、Ｂ６では、セルＢ５に対して鏡面関係のセクタ周波数及び偏波方式の設定とし、当該直交方向の間の方向で隣接する４つのセルＢ１、Ｂ３、Ｂ９、Ｂ７では、セルＢ５に対して左右反転の鏡面関係のセクタ周波数及び偏波方式の設定とすると、セルに隣接する８つのセルとの間で隣接するセクタに同一の通信周波数及び偏波方式を設定することができる。しかも、偏波方式を組み合わせることにより、使用する周波数を半減させることができ、周波数資源をより有効に活用することができる。
なお、この配置の基準となる直交方向は地磁気の方向を基準として設定するのが好ましく、このようにすれば設置作業において、遠隔の隣接する基地局の位置を予め把握せずとも、作業者は磁石をもって隣接する基地局の位置関係を把握することができ、広大なエリア内でも上記のような周波数及び偏波方式の設定を行うセル配置及びセクタ分割を行うことができる。
【００１８】
更に、本発明に係る無線通信システムでは、上記のような各無線通信システムで、各セルを構成する基地局に同一の偏波方式を設定し、更に、当該基地局とは異なる偏波方式を設定した基地局を当該セル配置に重ねて配置して偏波形式を異ならせた多重セル配置として、同一のエリア内に２つの基地局を配置して、干渉を生じさせることなくそれぞれの基地局による通信サービスを提供するようにしている。その具体的な構成の好ましい一例として、同一のセルを構成する一方の基地局の４つのセクタの通信周波数配置を時計回りに互いに異なる周波数であるＦ１、Ｆ３、Ｆ２、Ｆ４に設定し、他方の基地局のセクタの通信周波数配置を時計回りにＦ２、Ｆ４、Ｆ１、Ｆ３に設定している。
【００１９】
更に、本発明に係る無線通信システムでは、基地局の４つのセクタの通信周波数配置をＦ１＜Ｆ２＜Ｆ３＜Ｆ４又はＦ１＞Ｆ２＞Ｆ３＞Ｆ４の関係にある互いに異なる周波数であるＦ１、Ｆ３、Ｆ２、Ｆ４を時計回り又は反時計回りに設定した配置とし、周波数Ｆ２とＦ３との差をを周波数Ｆ１とＦ２との差及びＦ３とＦ４の差より大きく設定している。
同一のセルの隣接セクタ間では干渉を防止するためにできるだけ通信周波数の差が大きいことが望ましいことから、分割されたセクタに対して襷がけ形式で通信周波数を割り当てるのが好ましく、Ｆ１、Ｆ３、Ｆ２、Ｆ４を時計回り又は反時計回りに設定することとなる。しかしながら、同一のセルを構成する基地局のセクタを４分割すると、Ｆ２とＦ３が割り当てられるセクタが隣接することとなるので、これら周波数間を他のものより大きく設定し、同一セル内の隣接セクタ間での干渉を防止する。
【００２０】
なお、本発明に係る無線通信システムは、勿論指向性アンテナを有しない移動局への通信サービスを行うために用いることもできるが、上記のように加入者系無線アクセスシステムを構成するために固定端末局を収容するシステムに用いるのが好ましく、この場合には、基地局と指向線アンテナによって無線通信を行う固体端末局をセクタ内に配置し、当該固定端末局の通信周波数及び通信偏波方式を当該セクタに設定された通信周波数及び通信偏波方式と同一に設定すればよい。
【００２１】
【発明の実施の形態】
本発明に係る無線通信システムを実施例に基づいて具体的に説明する。
図１は、本発明の第１実施例に係る基地局のサービスエリアとセクタごとの使用周波数を示す平面図である。図において、Ｂ１〜Ｂ９は基地局、Ｆ１〜Ｆ４は互いに異なる通信周波数を示す。
なお、同図では、各セクターの位置関係を説明する都合上、東西南北を用いて説明するが、実際の配置がこれらの方向となっていなくてもよい。
【００２２】
基地局Ｂ５のセルにおいて、基地局に備えられた指向性アンテナの方向を調整して、４つのセクタを北西、北東、南東、南西方向を向くように配置し、使用する周波数をそれぞれＦ１、Ｆ３、Ｆ２、Ｆ４に設定する。
そして、基地局Ｂ５のセルの東西方向の隣接セルではセクタの東側と西側の周波数を入れ替えて設定する。すなわち、基地局Ｂ４とＢ６のセルのセクタ配置は、基地局Ｂ５セルにおいてＦ１とＦ３を入れ替え、また、Ｆ４とＦ２を入れ替えて、鏡面関係とする。また、基地局Ｂ５のセルの南北方向の隣接セルではセクタの北方向と南方向の周波数を入れ替えて設定する。すなわち、基地局Ｂ２とＢ８のセルのセクタ配置は、基地局Ｂ５セルにおいてＦ１とＦ４を入れ替え、また、Ｆ２とＦ３を入れ替えて、鏡面関係とする。
【００２３】
このルールに従い各セルを配置していくと、図１中の点線の円で示すように、隣接するセルの隣接するセクタは同一の周波数を使用することになり、各セクタ内に設定された固定端末局はそれぞれの基地局に指向して、他の基地局との干渉が生じない状態となる。
なお、更に言えば、当該ルールによると、基地局Ｂ５のセルの北東、北西、南東、南西方向の隣接セルでは、基地局Ｂ５のセクタとは左右反転の鏡面関係に周波数を設定することとなる。
【００２４】
加入者系無線アクセスシステムにおいては固定加入者局が２０ｄＢ以上のアンテナを使用することがＡＲＩＢＳＴＤ−Ｔ５９で義務づけられており、通常パラボラアンテナ等の指向性アンテナを使用する。このような高利得のアンテナは狭ビームを有しており、隣接する４つのセクタで同一の周波数を使用していても干渉とはならない。例えば、基地局Ｂ５のセルの周波数Ｆ１を使用するセクタに属する固定加入者局は、基地局Ｂ５の方向を向くため、隣接する基地局Ｂ１、Ｂ２およびＢ４のセルのＦ１を使用するセクタとの間で干渉を引き起こすことはない。
【００２５】
ここで、図２には、上記の配置設定において、他のセル（基地局）との干渉の発生可能性を示してある。
同図中のＣ１は基地局Ｂ１のセルのＦ２チャネルを使用するセクタに属する加入者局であり、この加入者局Ｃ１が同一チャネルによる干渉を受けるあるいは与える可能性のある最も近接したセクタは、経路を図中に矢印で示すように、基地局Ｂ３のセルのＦ２チャネルを使用するセクタである。
【００２６】
このように図１に示すセル配置によれば同一チャネルの干渉は１セルの間隔を離して起こり得るが、隣接するセルとの間での干渉は生じないので、１セルの間隔を隔てていることもあって、実用上において干渉は問題とならない。
また、実際の基地局の配置は机上検討の通りには行かないことも多く、周囲の環境や設置場所の確保など諸般の事情に左右されることがある。図３には、基地局の配置を正規の場所からずらして配置した場合の例を示してあるが、この場合にも、隣接の基地局との間で同一チャネル干渉を起こす可能性はなく、せいぜい１セルの間隔を隔てたセルとの干渉が理論上の可能性があるだけである。
【００２７】
なお、例えば加入者系無線アクセスシステムは準ミリ波やミリ波を使用して見通し通信を行うため、固定加入者局のアンテナと基地局のアンテナが見通せる関係でなければならないが、加入者局の設置後に周囲の環境の変化、特に新しい建造物の建築などによって、見通しでなくなる可能性は十分考えられる。
これに対して、本例では、加入者局の周囲に存在する他の３つの基地局も同じ周波数を使用しているので、加入者局のアンテナの方向を変えることで、使用する通信周波数を変更することなく他のいずれかの基地局と通信を行える可能性が十分にあり、このような加入者局のアンテナの方向調整という簡単な作業で周囲環境の変化に対応して通信接続を維持することもできる。
【００２８】
図４は、本発明の第２実施例に係る基地局のサービスエリアとセクタごとの使用周波数を示す平面図である。図において、Ｂ１〜Ｂ９は基地局、Ｆ１〜Ｆ４は互いに異なる通信周波数を示す。
なお、各セクタの位置関係を説明する都合上、東西南北を用いて説明するが、実際の配置がこれらの方向となっていなくともよい。
【００２９】
本例では、基地局Ｂ５のセルにおいて、その指向性アンテナの方向を設定して４つのセクタを北、東、南、西方向を向くように配置し、各セクタの通信に使用する周波数をそれぞれ、Ｆ１、Ｆ４、Ｆ２、Ｆ３とする。
そして、基地局Ｂ５セルの東西方向の隣接セルではセクタの東側と西側の周波数を入れ替える。すなわち、基地局Ｂ４とＢ６のセルのセクタ配置は、基地局Ｂ５セルにおいてＦ３とＦ４を入れ替えた鏡面関係とする。また、基地局Ｂ５セルの南北方向の隣接セルではセクタの北方向と南方向の周波数を入れ替える。すなわち、基地局Ｂ２とＢ８のセルのセクタ配置は、基地局Ｂ５セルにおいてＦ１とＦ２を入れ替えた鏡面関係とする。
【００３０】
このルールに従い各セルを配置していくと、図４中の点線の円で示すように、隣接するセルの隣接するセクタは同一の周波数を使用することになり、各セクタ内に設定された固定端末局はそれぞれの基地局に指向して、他の基地局との干渉が生じない状態となる。
なお、更に言えば、当該ルールによると、基地局Ｂ５のセルの北東、北西、南東、南西方向の隣接セルでは、基地局Ｂ５のセクタとは左右反転の鏡面関係に周波数を設定することとなる。
【００３１】
図５は、本発明の第３実施例に係る基地局のサービスエリアとセクタごとの使用周波数及び偏波方式を示す平面図である。図において、Ｂ１〜Ｂ９は基地局、Ｆ１、Ｆ２は互いに異なる通信周波数を示し、Ｖは垂直偏波、Ｈは水平偏波を使用することを示す。
なお、各セクタの位置関係を説明する都合上、東西南北を用いて説明するが、実際の配置がこれらの方向となっていなくともよい。
【００３２】
基地局Ｂ５のセルにおいて、その指向性アンテナの方向を設定して４つのセクタを北西、北東、南東、南西方向を向くように配置し、使用する周波数及び偏波方式をそれぞれ、Ｆ１Ｖ、Ｆ２Ｖ、Ｆ１Ｈ、Ｆ２Ｈに設定する。第１実施例と同様に、東西方向の隣接セルではセクタの東側と西側を入れ替え、南北方向の隣接セルではセクタの北方向と南方向を入れ替えて、鏡面関係としている。
【００３３】
このルールに従い各セルを配置していくと、図５中の点線の円で示すように、隣接するセルの隣接するセクタは同一の周波数及び同一の偏波方式を使用することになり、各セクタ内に設定された固定端末局はそれぞれの基地局に指向して、他の基地局との干渉が生じない状態となる。
更に言えば、当該ルールによると、基地局Ｂ５のセルの北東、北西、南東、南西方向の隣接セルでは、基地局Ｂ５のセクタとは左右反転の鏡面関係に周波数及び偏波方式を設定することとなる。
なお、本実施例においては垂直偏波と水平偏波を使用したが、右旋円偏波と左旋円偏波を用いてもよい。
【００３４】
図６は、本発明の第４実施例に係る基地局のサービスエリアとセクタごとの使用周波数及び偏波方式を示す平面図である。図において、Ｂ１〜Ｂ９は基地局、Ｆ１〜Ｆ４は互いに異なる通信周波数を示し、Ｖは垂直偏波、Ｈは水平偏波を使用することを示す。
なお、各セクタの位置関係を説明する都合上、東西南北を用いて説明するが、実際の配置がこれらの方向となっていなくともよい。
【００３５】
図６において、垂直偏波Ｖにのみ着目すれば、第1実施例（図１）と全く同じ配置となっている。
さて、本発明の第１実施例に基づいて既にセルの面展開を行っていることを想定し、この既設の基地局では、４つのセクタで垂直偏波Ｖを使用しているものとする。
既にサービスを行っている前記セルに基地局を増設する場合、新たに増設する基地局の位置は既設の基地局の位置と同じ位置とする。なお、図６には新たな基地局の記号を示していない。
【００３６】
新たな基地局では既設の基地局とは異なる水平偏波Ｈを使用するものに設定して既設の基地局との干渉を防止し、更に、本例では、既設のセクタとは時計回りに２セクタずつ使用周波数をずらして隣接しないように（更に言えば、指向性が反対となるように）し、周波数の面でも同一セクタ内で干渉が生じないようにしている。
【００３７】
このようにセクタの使用周波数と偏波方式が設定されたセルに対して、その隣接するセルでは第１実施例と同様なルールでセクタの周波数及び偏波方式を設定し、図６中の点線の円で示すように、隣接するセルの隣接するセクタは同一の周波数及び同一の偏波方式を使用するようにして、各セクタ内に設定された固定端末局はそれぞれの基地局に指向して、他の基地局との干渉が生じない状態とする。
更に言えば、当該ルールによると、基地局Ｂ５のセルの北、東、南、西方向の隣接セルでは、基地局Ｂ５のセクタとは鏡面関係に周波数及び偏波方式を設定し、基地局Ｂ５のセルの北東、北西、南東、南西方向の隣接セルでは、基地局Ｂ５のセクタとは左右反転の鏡面関係に周波数及び偏波方式を設定することとなる。
【００３８】
なお、既設のサービスエリアに基地局を増設するのではなく、初めから２つの基地局を同一エリアに配置した場合においても本実施例の結果と何ら変わりはないことは言うまでもない。
また、上記した各実施例の説明では、２つあるいは４つの周波数のみを用いてセル配置を面展開する方法について説明しているが、より多くの周波数を用いることができる場合には、本発明の実施例と組み合わせることによって同一チャネル干渉の生じる間隔をさらに大きくすることが可能であることは言うまでもない。
【００３９】
図７は、本発明の第５実施例に係る基地局のセクタごとの通信周波数の設定方法を説明する図である。なお、本例では、基地局の４つのセクタの通信周波数配置をＦ１＜Ｆ２＜Ｆ３＜Ｆ４又はＦ１＞Ｆ２＞Ｆ３＞Ｆ４の関係にある互いに異なる周波数Ｆ１、Ｆ３、Ｆ２、Ｆ４を時計回りに配置した図１の構成を用いて説明するが、これら周波数配置が反時計回りに設定されたものでも同様である。
【００４０】
同一セルの隣接セクタ間ではＩＲＦ（干渉軽減係数）が大きく取れるのが望ましく、このため隣接セクタ間の通信周波数は可能な限り差を大きくするのが望ましい。図１において、通信周波数Ｆ１〜Ｆ４の間にＦ１＜Ｆ２＜Ｆ３＜Ｆ４の関係があるとすれば、Ｆ２とＦ３の周波数が設定されるセクタが隣接してしまうこととなる。勿論、これらセクタ間でＩＲＦが十分取れる場合には問題とならないが、周波数資源を極力有効利用することができる割り当て構造を以下に説明する。
【００４１】
ＡＲＩＢ―ＳＴＤ―Ｔ５９によれば、通信周波数は使用周波数帯域を幾つかに分割したブロック単位で割り当てられる。そこで、本例では、図７（ａ）に示すように、一つのブロックに２チャネル配置し、互いに離れたブロック１とブロック４とを用いて、ブロック１にＦ１とＦ２を配置し、ブロック４にＦ３とＦ４を配置して、同図（ｂ）に示すように、周波数Ｆ２とＦ３との差を周波数Ｆ１とＦ２との差及びＦ３とＦ４の差より大きく設定している。
これにより、Ｆ２とＦ３が割り当てられる隣接セクタにおいても十分大きなＩＲＦ得られ、同一セル内の隣接セクタ間での干渉も防止される。
なお、ブロック内に５チャネル以上配置できる場合には、図７（ｃ）に示すように、Ｆ２とＦ３との間に予備チャネルを設ければよい。
【００４２】
【発明の効果】
以上説明したように、本発明に係る無線通信システムによれば、隣接セルの隣接セクタで同一周波数更には同一の偏波方式となる独特のセル配置によって、最低２つのチャネルのみでセルの面展開が可能となる無線通信システムのセル配置法を提供することができる。
また、本発明に係る無線通信システムは、基地局の位置が多少ずれた場合であっても同一チャネル干渉が隣接セルとの間で生じないという優れた特徴を有する無線通信システムのセル配置法を提供することができる。
【図面の簡単な説明】
【図１】本発明の第１実施例に係る基地局のセル配置を示す図である。
【図２】本発明の第１実施例に係る干渉防止効果を説明する図である。
【図３】本発明の第１実施例に係る配置ずれの影響を説明する図である。
【図４】本発明の第２実施例に係る基地局のセル配置を示す図である。
【図５】本発明の第３実施例に係る基地局のセル配置を示す図である。
【図６】本発明の第４実施例に係る基地局のセル配置を示す図である。
【図７】本発明の第５実施例に係る通信周波数設定を説明する図である。
【図８】加入者系無線アクセスシステムの一例を示す図である。
【図９】セクタアンテナの構造を説明する図である。
【図１０】従来の基地局のセル配置を示す図である。
【図１１】従来の基地局のセル配置による不具合を説明する図である。
【符号の説明】
Ｂ１〜Ｂ９：基地局、Ｃ１、Ｃ２：加入者局、
Ｆ１〜Ｆ４：通信周波数、Ｖ、Ｈ：偏波方式、[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless communication system that divides a wireless communication area into a plurality of cells by arranging a plurality of base stations, and enables the same frequency to be repeatedly used in a plurality of cells. The present invention relates to a technology for realizing a P-MP system of a subscriber radio access system that effectively uses a quasi-millimeter wave band or a limited frequency band of the millimeter wave band.
[0002]
[Prior art]
For example, a subscriber wireless access system using wireless communication called WLL (wireless local loop) or FWA (Fixed wireless access) is known. As shown in FIG. 8, the subscriber radio access system connects a base station 1 installed by a telecommunications carrier and a subscriber station 2 installed on each side of a plurality of user premises by radio communication. Yes, the base station 1 and the subscriber station 2 can communicate wirelessly so that data communication can be performed between the LANs 3 connected to different subscriber stations 2, and the public communication network connected to the base station 1 Data communication can be performed with another subscriber LAN via the backbone network 4.
The base station 1 accommodates a large number of subscriber stations 2, and such a one-to-multidirectional wireless facility is called a P-MP (Point-Multi Point) system.
[0003]
By disposing a plurality of base stations 1 in such a manner, it is possible to provide a service to a large number of subscriber stations 2 while covering a certain area, but use limited frequency resources effectively. Therefore, the same communication frequency must be used repeatedly.
Such repeated use of frequencies has been performed for a long time in the field of mobile communications found in automobiles and mobile phones, but the same frequency could not be used in adjacent base stations in order to prevent interference.
[0004]
The P-MP system uses a high communication frequency such as a quasi-millimeter wave band or a millimeter wave band and performs line-of-sight wireless communication using a high gain antenna. This standard is defined by ARIB STD-T59. ing. According to this standard, it is stipulated that a communication frequency must be 26 GHz band or 38 GHz band, and a high gain antenna of 20 dBi or more must be used for a subscriber station.
[0005]
For these reasons, the antenna 6 of the base station 1 uses a directional antenna such as a parabolic antenna or a sector antenna to realize repeated use of frequency and high gain.
A plurality of parabolic antennas are installed in the base station, and these parabolic antennas are directed in different directions, and the horizontal plane is divided into a plurality of sectors to achieve repeated use of frequencies and high gain. It was. Further, for example, as shown in FIG. 9, the sector antenna divides a disk-shaped antenna substrate 10 into four sectors A to D by a shielding plate 11, and provides antenna elements 12 in the sectors A to D, respectively. ˜D are each configured as a directional antenna, and the horizontal direction is divided into four by sectors A to D, and repeated use of frequencies is realized and high gain is realized by sector division.
[0006]
In the subscriber radio access system, the fixed subscriber station 2 accommodated in each sector of the base station 1 also uses the directional antenna 7 to cause interference between sectors due to repeated use of the communication frequency. It is preventing.
Here, as a cell configuration method in a wireless communication system in which a communication service area by a base station is formed around a base station as a center and a wide area is covered by a plurality of cells by distributing a plurality of base stations. The invention described in JP-A-10-42352 is known.
[0007]
The present invention is as shown in FIG. 10, in which B1 to B4 are base stations, communication service areas (cells) of the base stations are indicated by hexagons for convenience, and F1 to F3 are antennas (sectors). ) Used frequency (channel). In other words, in the present invention, m sectors (m is a positive number of 2 or more) in a cell are set to have the same frequency so as to prevent interference between sectors.
[0008]
Here, in the configuration as in the present invention, C1 is one of the subscriber stations belonging to the sector using the F2 channel of the base station B2, and as shown by the arrows in FIG. The closest base station to which station C1 may receive or give interference from the same channel is B4. With such a configuration, co-channel interference can occur at an interval of one cell. However, with such interference, the intended communication quality can be maintained and no practical trouble occurs.
[0009]
However, the actual arrangement of base stations often does not go as planned, and may be affected by various circumstances such as the surrounding environment and securing the installation location, resulting in interference between cells. . FIG. 11 shows an example in which the installation position of the base station B3 is deviated from the regular place, and the subscriber station C2 belonging to the sector using the F2 channel of the base station B3 is connected to the adjacent base station B2. Interference may occur with sectors that use the F2 channel.
In addition, the cell plane development cannot be performed unless there are at least three cell arrangements formed of hexagons. Even if there are four channels that can be used, it is expected that it is difficult to use these four channels efficiently.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to provide a radio communication system having a cell arrangement structure that can prevent interference with adjacent cells and can be realized if there are at least two communication frequencies to be used.
In particular, an object of the present invention is to provide an optimal cell arrangement for a subscriber radio access system with a four-sector configuration that is not employed in a conventional cellular system.
Further objects of the present invention will be apparent from the following description.
[0011]
[Means for Solving the Problems]
A wireless communication system according to the present invention is a communication system in which a communication service area by a base station is formed as a cell with a base station as a center, and a plurality of cells are formed by distributing a plurality of base stations. By using a directional antenna in a station, the cell of the base station is divided into four sectors, and the same communication frequency is set in adjacent sectors between adjacent cells.
[0012]
That is, when four adjacent cells are captured, the base station of each cell has directivity inward in the horizontal plane in the sectors adjacent to these cells. When a fixed subscriber station is installed in these adjacent sectors with directivity to the base station in the sector, the fixed subscriber station exhibits directivity in the direction of the base station to which it belongs, but the base station of another adjacent sector. The base station of the adjacent sector and the fixed subscriber station do not face each other, and the base station of the adjacent sector is not connected to the wireless communication of the fixed subscriber station. The interference of the relationship does not occur.
[0013]
The wireless communication system according to the present invention is a communication system in which a communication service area by a base station is formed as a cell with a base station as a center, and a plurality of cells are formed by distributing a plurality of base stations. By using a directional antenna for the base station, the cell of the base station is divided into four sectors, different communication frequencies are set in adjacent sectors in the same cell, and other cells adjacent in the orthogonal direction The communication frequency setting of each sector is mirror-like, and the communication frequency setting of each sector is mirror-reversed in the horizontal direction with other cells adjacent in the orthogonal direction. The frequency is set.
In the radio communication system according to the present invention, the cell of the base station is divided into sectors oriented in four directions with reference to the geomagnetic direction.
[0014]
For example, as shown in FIG. 1 to be described later, the cell of the base station B5 is divided into four sectors each directed to the northwest, northeast, southeast, and southwest, and communication frequencies F1, F3, F2, and F4 are set in each cell. In this case, if eight cells adjacent to the base station B5 are captured, the four cells B2, B8, B4, and B6 adjacent in the north-south and east-west directions are set to mirror-related sector frequency settings for the cell B5. In the four cells B1, B3, B9, and B7 that are adjacent in the direction between the orthogonal directions, the sector frequency setting that is mirror-reversed with respect to the cell B5 is set between the eight cells adjacent to the cell. The same communication frequency can be set in adjacent sectors.
In addition, it is preferable to set the orthogonal direction as a reference for this arrangement with reference to the direction of geomagnetism, and in this way, in the installation work, the operator can know the position of a remote adjacent base station in advance The positional relationship between adjacent base stations can be grasped with a magnet, and cell arrangement and sector division for performing frequency setting as described above can be performed even in a large area.
[0015]
The wireless communication system according to the present invention is a communication system in which a communication service area by a base station is formed as a cell with a base station as a center, and a plurality of cells are formed by distributing a plurality of base stations. By using a directional antenna for a base station, the cell of the base station is divided into four sectors, and the same communication frequency and polarization method are set in adjacent sectors between adjacent cells.
That is, interference can be prevented by changing the polarization method even at the same communication frequency. However, in the present invention, the fixed subscriber station in the sector is different between adjacent sectors of adjacent cells as described above. Since the directivity does not face the base station of the sector (especially when the subscriber station uses a high gain antenna of 20 dBi or more), the same communication frequency and polarization method are applied to adjacent sectors between adjacent cells. It is set.
[0016]
The wireless communication system according to the present invention is a communication system in which a communication service area by a base station is formed as a cell with a base station as a center, and a plurality of cells are formed by distributing a plurality of base stations. The base station cell is divided into four sectors by using a directional antenna in the base station, and at least one of the communication frequency and the polarization method is set to be different in the adjacent sector in the same cell. The other cells adjacent in the orthogonal direction have a mirror-like relationship between the communication frequency and the polarization method of each sector, and the other cells adjacent in the orthogonal direction have the communication frequency and the polarization method of each sector. The same communication frequency and polarization method are set in adjacent sectors between adjacent cells. That is, interference between adjacent sectors in the same cell can be prevented by using different polarization methods, such as vertical and horizontal polarization, right-handed circular polarization and left-handed circular polarization, even at the same communication frequency. Since the directivity does not oppose between adjacent sectors of adjacent cells as described above, the same communication frequency and polarization method can be set.
In the radio communication system according to the present invention, the cell of the base station is divided into sectors oriented in four directions with reference to the geomagnetic direction.
[0017]
For example, as shown in FIG. 5 to be described later, the cell of the base station B5 is divided into four sectors each directed to the northwest, northeast, southeast, and southwest, and the communication frequency and polarization method (V: vertical polarization) are divided into each cell. When F1V, F2V, F1H, and F2H are set as wave, H: horizontal polarization), if eight cells adjacent to the base station B5 are captured, four cells B2 and B8 adjacent in the north-south and east-west directions , B4, and B6, the sector frequency and the polarization method are mirror-related with respect to the cell B5, and the four cells B1, B3, B9, and B7 adjacent to each other in the direction between the orthogonal directions are set with respect to the cell B5. Thus, when setting the sector frequency and the polarization method in the mirror-reversed mirror plane, it is possible to set the same communication frequency and polarization method in the adjacent sectors between the eight cells adjacent to the cell. Moreover, by combining the polarization methods, the frequency to be used can be halved, and frequency resources can be utilized more effectively.
In addition, it is preferable to set the orthogonal direction as a reference for this arrangement with reference to the direction of geomagnetism, and in this way, in the installation work, the operator can know the position of a remote adjacent base station in advance The positional relationship between adjacent base stations can be grasped with a magnet, and cell arrangement and sector division for setting the frequency and polarization method as described above can be performed even in a large area.
[0018]
Furthermore, in the radio communication system according to the present invention, in each radio communication system as described above, the same polarization scheme is set for the base stations constituting each cell, and furthermore, a polarization scheme different from the base station is set. As a multi-cell arrangement in which the set base stations are overlapped with the cell arrangement and the polarization formats are different, two base stations are arranged in the same area, and each base station does not cause interference. We are trying to provide communication services. As a preferable example of the specific configuration, the communication frequency arrangement of four sectors of one base station configuring the same cell is set to different frequencies F1, F3, F2, and F4 in the clockwise direction, and the other The communication frequency arrangement of the base station sector is set to F2, F4, F1, and F3 in the clockwise direction.
[0019]
Further, in the wireless communication system according to the present invention, the communication frequency arrangement of the four sectors of the base station is different from each other in the frequencies F1, F3, which are in a relationship of F1 <F2 <F3 <F4 or F1>F2>F3> F4. The arrangement is such that F2 and F4 are set clockwise or counterclockwise, and the difference between the frequencies F2 and F3 is set larger than the difference between the frequencies F1 and F2 and the difference between F3 and F4.
In order to prevent interference between adjacent sectors in the same cell, it is desirable that the difference in communication frequency is as large as possible. Therefore, it is preferable to assign the communication frequency to the divided sectors in a striking manner, F1, F3, F2 and F4 are set clockwise or counterclockwise. However, if the base station sectors constituting the same cell are divided into four, the sectors to which F2 and F3 are allocated are adjacent to each other. To prevent interference between them.
[0020]
The radio communication system according to the present invention can of course be used for providing a communication service to a mobile station that does not have a directional antenna, but is fixed to configure the subscriber radio access system as described above. It is preferably used for a system that accommodates a terminal station. In this case, a solid-state terminal station that performs wireless communication with a base station and a directional antenna is arranged in the sector, and the communication frequency and communication polarization method of the fixed terminal station. May be set to be the same as the communication frequency and communication polarization method set for the sector.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
A wireless communication system according to the present invention will be specifically described based on an embodiment.
FIG. 1 is a plan view showing a service area of a base station and a used frequency for each sector according to the first embodiment of the present invention. In the figure, B1 to B9 indicate base stations, and F1 to F4 indicate different communication frequencies.
In the figure, for convenience of explaining the positional relationship of each sector, explanation will be made using east, west, south, and north, but the actual arrangement may not be in these directions.
[0022]
In the cell of the base station B5, the direction of the directional antenna provided in the base station is adjusted, and the four sectors are arranged to face the northwest, northeast, southeast, and southwest directions, and the frequencies used are F1 and F3, respectively. , F2, and F4.
In the adjacent cell in the east-west direction of the cell of the base station B5, the frequencies on the east side and the west side of the sector are switched and set. That is, the sector arrangement of the cells of the base stations B4 and B6 has a mirror-surface relationship by exchanging F1 and F3 and exchanging F4 and F2 in the base station B5 cell. Further, in the adjacent cell in the north-south direction of the cell of the base station B5, the frequency in the north direction and the south direction of the sector are switched and set. That is, the sector arrangement of the cells of the base stations B2 and B8 has a mirror-surface relationship by exchanging F1 and F4 and exchanging F2 and F3 in the base station B5 cell.
[0023]
When each cell is arranged according to this rule, as shown by a dotted circle in FIG. 1, adjacent sectors in adjacent cells use the same frequency, and fixed sectors set in each sector are fixed. The terminal station is directed to each base station and is in a state in which no interference with other base stations occurs.
In addition, according to the rule, in the adjacent cells in the northeast, northwest, southeast, and southwest directions of the cell of the base station B5, the frequency is set in a mirror-reverse relationship with the sector of the base station B5. .
[0024]
In the subscriber radio access system, it is obliged by ARIB STD-T59 that a fixed subscriber station uses an antenna of 20 dB or more, and a directional antenna such as a parabolic antenna is usually used. Such a high-gain antenna has a narrow beam and does not cause interference even when the same frequency is used in four adjacent sectors. For example, the fixed subscriber station belonging to the sector using the frequency F1 of the cell of the base station B5 faces the direction of the base station B5, and therefore, with the sector using the F1 of the cells of the adjacent base stations B1, B2 and B4 There is no interference between them.
[0025]
Here, FIG. 2 shows the possibility of interference with other cells (base stations) in the above arrangement setting.
C1 in the figure is a subscriber station belonging to a sector that uses the F2 channel of the cell of the base station B1, and the closest sector to which the subscriber station C1 may receive or give interference by the same channel is: The path is a sector that uses the F2 channel of the cell of the base station B3 as indicated by an arrow in the figure.
[0026]
As described above, according to the cell arrangement shown in FIG. 1, the interference of the same channel can occur at an interval of one cell, but the interference between adjacent cells does not occur, so the interval of one cell is separated. For this reason, interference is not a problem in practical use.
In addition, the actual location of base stations often does not go as planned, and may be affected by various circumstances such as the surrounding environment and securing the installation location. FIG. 3 shows an example in which the arrangement of the base stations is shifted from the regular place, but in this case also, there is no possibility of causing the same channel interference with the adjacent base station, At best, there is only a theoretical possibility of interference with cells separated by one cell.
[0027]
In addition, for example, because the subscriber radio access system performs line-of-sight communication using quasi-millimeter waves and millimeter waves, the antenna of the fixed subscriber station and the antenna of the base station must be visible, but the subscriber station After installation, there is a good chance that it will be out of sight due to changes in the surrounding environment, especially the construction of new buildings.
On the other hand, in this example, the other three base stations existing around the subscriber station use the same frequency. Therefore, by changing the direction of the antenna of the subscriber station, the communication frequency to be used is changed. It is possible to communicate with one of the other base stations without change, and the communication connection can be maintained in response to changes in the surrounding environment with the simple task of adjusting the direction of the antenna of such a subscriber station. You can also
[0028]
FIG. 4 is a plan view showing the service area of the base station and the used frequency for each sector according to the second embodiment of the present invention. In the figure, B1 to B9 indicate base stations, and F1 to F4 indicate different communication frequencies.
In addition, for convenience of explaining the positional relationship of each sector, explanation will be made using east, west, south, and north, but the actual arrangement may not be in these directions.
[0029]
In this example, in the cell of the base station B5, the direction of the directional antenna is set, and four sectors are arranged to face the north, east, south, and west directions, and the frequencies used for communication of each sector are respectively set. , F1, F4, F2, and F3.
And the frequency of the east side and the west side of the sector is switched in the adjacent cell in the east-west direction of the base station B5 cell. That is, the sector arrangement of the cells of the base stations B4 and B6 is a mirror-surface relationship in which F3 and F4 are interchanged in the base station B5 cell. In addition, the frequency in the north direction and the south direction of the sector are switched in adjacent cells in the north-south direction of the base station B5 cell. That is, the sector arrangement of the cells of the base stations B2 and B8 is a mirror relationship in which F1 and F2 are interchanged in the base station B5 cell.
[0030]
When each cell is arranged according to this rule, as shown by the dotted circle in FIG. 4, adjacent sectors in adjacent cells use the same frequency, and the fixed frequency set in each sector is set. The terminal station is directed to each base station and is in a state in which no interference with other base stations occurs.
In addition, according to the rule, in the adjacent cells in the northeast, northwest, southeast, and southwest directions of the cell of the base station B5, the frequency is set in a mirror-reverse relationship with the sector of the base station B5. .
[0031]
FIG. 5 is a plan view showing a service area of a base station according to a third embodiment of the present invention, a used frequency and a polarization method for each sector. In the figure, B1 to B9 indicate base stations, F1 and F2 indicate different communication frequencies, V indicates vertical polarization, and H indicates horizontal polarization.
In addition, for convenience of explaining the positional relationship of each sector, explanation will be made using east, west, south, and north, but the actual arrangement may not be in these directions.
[0032]
In the cell of the base station B5, the direction of the directional antenna is set and the four sectors are arranged so as to face the northwest, northeast, southeast, and southwest directions, and the frequency and polarization method to be used are F1V, F2V, Set to F1H and F2H. As in the first embodiment, the east side and the west side of the sector are exchanged in the adjacent cells in the east-west direction, and the north direction and the south direction of the sector are exchanged in the adjacent cells in the north-south direction.
[0033]
When each cell is arranged according to this rule, as shown by a dotted circle in FIG. 5, adjacent sectors in adjacent cells use the same frequency and the same polarization method, and each sector. The fixed terminal stations set in are directed to the respective base stations and no interference with other base stations occurs.
Furthermore, according to the rule, in the adjacent cells in the northeast, northwest, southeast, and southwest directions of the cell of the base station B5, the frequency and the polarization method are set in the mirror-reverse relationship with the sector of the base station B5. It becomes.
In this embodiment, vertical polarization and horizontal polarization are used, but right-hand circular polarization and left-hand circular polarization may be used.
[0034]
FIG. 6 is a plan view showing the service area of the base station and the used frequency and polarization method for each sector according to the fourth embodiment of the present invention. In the figure, B1 to B9 indicate base stations, F1 to F4 indicate different communication frequencies, V indicates vertical polarization, and H indicates horizontal polarization.
In addition, for convenience of explaining the positional relationship of each sector, explanation will be made using east, west, south, and north, but the actual arrangement may not be in these directions.
[0035]
In FIG. 6, if attention is paid only to the vertical polarization V, the arrangement is the same as that of the first embodiment (FIG. 1).
Now, assuming that the cell plane has already been expanded based on the first embodiment of the present invention, it is assumed that the existing base station uses vertical polarization V in four sectors.
When a base station is added to the already serviced cell, the location of the newly added base station is the same as the location of the existing base station. FIG. 6 does not show a new base station symbol.
[0036]
The new base station is set to use a horizontally polarized wave H different from that of the existing base station to prevent interference with the existing base station. The use frequency is shifted for each sector so as not to be adjacent to each other (more specifically, the directivity is opposite), so that interference does not occur within the same sector in terms of frequency.
[0037]
For the cell in which the sector use frequency and the polarization method are set as described above, the sector frequency and the polarization method are set in the adjacent cell according to the same rule as in the first embodiment, and the dotted line in FIG. As shown by circles, adjacent sectors in adjacent cells use the same frequency and the same polarization method, and fixed terminal stations set in each sector are directed to respective base stations. In a state in which interference with other base stations does not occur.
Furthermore, according to the rule, in the adjacent cells in the north, east, south, and west directions of the cell of the base station B5, the frequency and polarization method are set in a mirror relationship with the sector of the base station B5, and the base station B5 In the adjacent cells in the northeast, northwest, southeast, and southwest directions of this cell, the frequency and polarization method are set in a mirror-reversed mirror relationship with the sector of the base station B5.
[0038]
Needless to say, even if two base stations are arranged in the same area from the beginning instead of adding a base station to the existing service area, there is no difference from the result of the present embodiment.
Further, in the description of each of the above embodiments, the method for expanding the cell arrangement using only two or four frequencies has been described. However, when more frequencies can be used, the present invention can be used. It goes without saying that it is possible to further increase the interval at which co-channel interference occurs by combining with the above embodiment.
[0039]
FIG. 7 is a diagram for explaining a communication frequency setting method for each sector of the base station according to the fifth embodiment of the present invention. In this example, the communication frequency arrangement of the four sectors of the base station is clockwise with different frequencies F1, F3, F2, and F4 having a relationship of F1 <F2 <F3 <F4 or F1>F2>F3> F4. Although the description will be made using the arrangement of FIG. 1 arranged, the same applies to those in which these frequency arrangements are set counterclockwise.
[0040]
It is desirable to have a large IRF (interference mitigation factor) between adjacent sectors in the same cell. For this reason, it is desirable that the communication frequency between adjacent sectors be as large as possible. In FIG. 1, if there is a relationship of F1 <F2 <F3 <F4 between the communication frequencies F1 to F4, sectors in which the frequencies of F2 and F3 are set are adjacent to each other. Of course, there will be no problem when sufficient IRF can be obtained between these sectors, but an allocation structure capable of making effective use of frequency resources as much as possible will be described below.
[0041]
According to ARIB-STD-T59, the communication frequency is assigned in units of blocks obtained by dividing the use frequency band into several. Therefore, in this example, as shown in FIG. 7A, two channels are arranged in one block, and blocks 1 and 4 separated from each other are used, and F1 and F2 are arranged in block 1, and block 4 F3 and F4 are arranged at the same position, and the difference between the frequencies F2 and F3 is set larger than the difference between the frequencies F1 and F2 and the difference between F3 and F4 as shown in FIG.
As a result, a sufficiently large IRF can be obtained even in adjacent sectors to which F2 and F3 are allocated, and interference between adjacent sectors in the same cell is prevented.
If five or more channels can be arranged in the block, a spare channel may be provided between F2 and F3 as shown in FIG.
[0042]
【The invention's effect】
As described above, according to the wireless communication system according to the present invention, the cell plane deployment with at least two channels can be achieved by the unique cell arrangement having the same frequency and the same polarization method in the adjacent sector of the adjacent cell. Thus, it is possible to provide a cell arrangement method for a wireless communication system.
In addition, the radio communication system according to the present invention provides a cell arrangement method for a radio communication system having an excellent feature that co-channel interference does not occur between adjacent cells even when the position of the base station is slightly shifted. Can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a cell arrangement of a base station according to a first embodiment of the present invention.
FIG. 2 is a diagram for explaining an interference preventing effect according to the first embodiment of the present invention.
FIG. 3 is a diagram for explaining the influence of misalignment according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating a cell arrangement of a base station according to a second embodiment of the present invention.
FIG. 5 is a diagram illustrating a cell arrangement of a base station according to a third embodiment of the present invention.
FIG. 6 is a diagram illustrating a cell arrangement of a base station according to a fourth embodiment of the present invention.
FIG. 7 is a diagram for explaining communication frequency setting according to a fifth embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a subscriber wireless access system.
FIG. 9 is a diagram illustrating the structure of a sector antenna.
FIG. 10 is a diagram showing a cell arrangement of a conventional base station.
FIG. 11 is a diagram for explaining a problem caused by cell arrangement of a conventional base station.
[Explanation of symbols]
B1-B9: Base station, C1, C2: Subscriber station,
F1 to F4: communication frequency, V, H: polarization method,

Claims

In a wireless communication system in which a communication service area by the base station is formed as a cell around the base station as a center, and a plurality of cells are formed by distributing a plurality of base stations,
By using a directional antenna for the base station, the cell of the base station is divided into four sectors,
Set the same communication frequency in adjacent sectors between adjacent cells ,
The communication frequency arrangement of the four sectors of the base station is F1 <F2 <F3 <F4 or F1>F2>F3> F4, F1, F3, F2, and F4 which are different from each other in the clockwise or counterclockwise direction. A wireless communication system, characterized in that a set arrangement is set, and a difference between frequencies F2 and F3 is set larger than a difference between frequencies F1 and F2 and a difference between F3 and F4 .

In a wireless communication system in which a communication service area by the base station is formed as a cell around the base station as a center, and a plurality of cells are formed by distributing a plurality of base stations,
By using a directional antenna for the base station, the cell of the base station is divided into four sectors,
Set different communication frequencies for adjacent sectors in the same cell,
The communication frequency setting of each sector is a mirror surface relationship with other cells adjacent in the orthogonal direction, and the communication frequency setting of each sector is adjacent to the other cells adjacent in the orthogonal direction as a mirror surface relationship that is horizontally reversed. Set the same communication frequency in adjacent sectors between cells ,
The communication frequency arrangement of the four sectors of the base station is F1 <F2 <F3 <F4 or F1>F2>F3> F4, F1, F3, F2, and F4 which are different from each other in the clockwise or counterclockwise direction. A wireless communication system, characterized in that a set arrangement is set, and a difference between frequencies F2 and F3 is set larger than a difference between frequencies F1 and F2 and a difference between F3 and F4 .

In a wireless communication system in which a communication service area by the base station is formed as a cell around the base station as a center, and a plurality of cells are formed by distributing a plurality of base stations,
By using a directional antenna for the base station, the cell of the base station is divided into sectors directed in four directions based on the geomagnetic direction,
Set different communication frequencies for all sectors in the same cell,
The communication frequency setting of each sector is a mirror relationship with other cells adjacent in the orthogonal direction, and the adjacent cell is a mirror relationship in which the communication frequency setting of each sector is horizontally reversed with other cells adjacent in the orthogonal direction. Set the same communication frequency between adjacent sectors ,
The communication frequency arrangement of the four sectors of the base station is F1 <F2 <F3 <F4 or F1>F2>F3> F4, F1, F3, F2, and F4 which are different from each other in the clockwise or counterclockwise direction. A wireless communication system, characterized in that a set arrangement is set, and a difference between frequencies F2 and F3 is set larger than a difference between frequencies F1 and F2 and a difference between F3 and F4 .

In a wireless communication system in which a communication service area by the base station is formed as a cell around the base station as a center, and a plurality of cells are formed by distributing a plurality of base stations,
By using a directional antenna for the base station, the cell of the base station is divided into four sectors,
Between adjacent cells, set the same communication frequency and polarization method in adjacent sectors ,
The communication frequency arrangement of the four sectors of the base station is F1 <F2 <F3 <F4 or F1>F2>F3> F4, F1, F3, F2, and F4 which are different from each other in the clockwise or counterclockwise direction. A wireless communication system, characterized in that a set arrangement is set, and a difference between frequencies F2 and F3 is set larger than a difference between frequencies F1 and F2 and a difference between F3 and F4 .

In a wireless communication system in which a communication service area by the base station is formed as a cell around the base station as a center, and a plurality of cells are formed by distributing a plurality of base stations,
By using a directional antenna for the base station, the cell of the base station is divided into four sectors ,
The setting of the communication frequency and polarization method of each sector is mirror-related with other cells adjacent in the orthogonal direction, and the setting of the communication frequency and polarization method of each sector with other cells adjacent in the orthogonal direction. As the mirror relationship of right and left reversal, between the adjacent cells, set the same communication frequency and polarization method in the adjacent sector ,
The communication frequency arrangement of the four sectors of the base station is F1 <F2 <F3 <F4 or F1>F2>F3> F4, F1, F3, F2, and F4 which are different from each other in the clockwise or counterclockwise direction. A wireless communication system, characterized in that a set arrangement is set, and a difference between frequencies F2 and F3 is set larger than a difference between frequencies F1 and F2 and a difference between F3 and F4 .

In a wireless communication system in which a communication service area by the base station is formed as a cell around the base station as a center, and a plurality of cells are formed by distributing a plurality of base stations,
By using a directional antenna for the base station, the cell of the base station is divided into sectors directed in four directions based on the geomagnetic direction ,
The other cell adjacent in the orthogonal direction has a mirror-like relationship between the communication frequency and polarization method of each sector, and the other cell adjacent in the orthogonal direction has the communication frequency and polarization method setting of each sector. As a mirror relationship of left and right reversal, set the same communication frequency and polarization method in adjacent sectors between adjacent cells ,
The communication frequency arrangement of the four sectors of the base station is F1 <F2 <F3 <F4 or F1>F2>F3> F4, F1, F3, F2, and F4 which are different from each other in the clockwise or counterclockwise direction. A wireless communication system, characterized in that a set arrangement is set, and a difference between frequencies F2 and F3 is set larger than a difference between frequencies F1 and F2 and a difference between F3 and F4 .

The wireless communication system according to any one of claims 1 to 6,
The same polarization scheme was set for the base stations that make up each cell, and the base stations with different polarization schemes from the base stations were placed on top of the cell layout to change the polarization format. A wireless communication system, characterized in that a multi-cell arrangement is adopted.

The wireless communication system according to claim 7,
The communication frequency arrangement of the four sectors of one base station constituting the same cell is set to different frequencies F1, F3, F2, and F4 in the clockwise direction, and the communication frequency arrangement of the sector of the other base station is set to the clock. A wireless communication system characterized in that F2, F4, F1, and F3 are set around.

The wireless communication system according to any one of claims 1 to 8 ,
Solid terminal station that performs radio communication with a base station by directional antennas arranged in a sector, the communication frequency and communication polarization mode of the fixed terminal station in the same communication frequency and communication polarization mode is set to the sector A wireless communication system characterized by being set.